Viscosity of oils

Oxidation first produces soluble oxygenated compounds of molecular weights between 500 and 3000 that increase the viscosity of oil then they polymerize, precipitate, and form deposits. Oxidation also causes formation of low molecular weight organic acids which are very corrosive to metals. 

Unlike gases, liquid viscosity decreases as temperature increases, as the molecules move further apart and decrease their internal friction. Like gases, oil viscosity increases as the pressure increases, at least above the bubble point. Below the bubble point, when the solution gas is liberated, oil viscosity increases because the lighter oil components of the oil (which lower the viscosity of oil) are the ones which transfer to the gas phase. 

Occasionally polymers are used to increase the viscosity of oil-base and synthetic-base muds. The polymers for this use are typically sulfonated polystyrenes or ethylene—propylene terpolymers (EPDM) (54,55). Such polymers are usually used in conjunction with an organopbilic clay. 

SAE numbers have been established by the Society of Automotive Engineers to specify ranges of SUS viscosities of oils at SAE test temperatures. Winter numbers (5W, low, 20W) are determined by tests at 0°F. Summer numbers (20W, SOW, etc.) designate the SUS range at 210°F. Table 40.1 is a chart of the temperature ranges. 

Viscosity is one of the most important properties of lubricating oil. The actual viscosity of oil samples is compared to an unused sample to determine the thinning of thickening of the sample during use. Excessively low viscosity will reduce the oil film strength, weakening its ability to prevent metal-to-metal contact. 

Saybolt viscosity (ASTM D-88) is the most popular method of measuring the viscosity of oils such as FCC feed. This method covers two procedures ... 

Heavy fuel oils must be heated to provide a suitably low viscosity for delivery to the burner and for atomization. The viscosity of oils at the burner typically should be between 100 and 150 Saybolt Seconds Universal (SSU). 

Another EOR approach to reducing the viscosity of oil in the reservoir is ntiscible flooding— the injection of fluids that mix with the oil under reservoir conditions. Such fluids include carbon dioxide, light hydrocarbons, and ititrogen. Supply and cost of carbon dioxide are often more favorable than for other injectants. Extensive research and field testing have established the techiucal viability of miscible flooding, and a nnmber of commercial carbon dioxide miscible flooding projects are in operation. 

As we already know, the viscosity of oil near to the solid wall is limited to a hnite magnitude (whose value approaches the value of the relevant solid). Thus, the variation of viscosity along the direction normal to the wall plane can be described by a function as follows [31]... 

Figure 22 shows variation of the him thickness with velocities. The three curves in the hgure are results from the EHL solution, experimental data, and TFL solution, respectively. The maximum Hertzian contact pressure is 0.125 GPa and the atmosphere viscosity of oil is 0.062 Pa s. While the velocity is higher than 100 mm s, i.e., the him is thicker than 50 nm, all the results from EHL, TFL, and experimental data are very close to each other, which indicate that when in the EHL lubrication regime, bulk viscosity plays the main role and the results of three types are close to each other. When... 

Laboratory studies indicate that aquathermolysis can be used to aid in the remediation of waste oils, chromium (Cr VI) and volatile organic compounds (VOCs) in contaminated soils and aquifers. Aquathermolysis is particularly useful in lowering the viscosity of oil and increasing its mobility to facilitate further treatment. Potential applications range from treating household and industrial refuse to destruction of chemical warfare agents. 

The viscosity of oil has an important influence on the speed of entrance into the plant. As the viscosity decreases, the rate of penetration increases, as does the speed at which visible injury symptoms develop. Vapor pressure and viscosity curves for n-decane are given in Figure 2. If the two are of equal importance in hydrocarbon penetration, they would approximately cancel each other. Such a cancellation may explain the lack of a marked change in hydrocarbon toxicity with variations in temperature. 

Gelling Agents Chemicals drat are used to increase the viscosity of oils or odier substances applied to reduce the rate of spread over a water body s surface during a spill. 

Before 1925, there were a few compounded oils made for special purposes, such as lubrication of marine engines and steam cylinders, but additives were not used in automotive crankcase oils. In the 1930 s, chemical compounds made by condensation of chlorinated paraffin wax with naphthalene were found to lower the pour points of oils. Pour depressants (9) apparently are adsorbed on small wax crystals which separate from oils when they are chilled. The protective adsorbed layer of additive prevents the normal interlacing of larger wax crystals which forms a gel. In 1934 polymerized unsaturated hydrocarbons first came into large scale commercial use to lower the temperature coefficient of viscosity of oils. Other compounds for increasing the viscosity index of oils have since become common. 

It is seen that droplet falling velocity is one of the decisive factor in efficient dehydration and optimum results are obtained when the viscosity of oil is between 5 to 10 centlstokes. Normally the viscosity of oil at room temperature is much higher than tnie value. Therefore, addition of heat is essential and it is a function of crude characteristics. 

From this equation It is evident that the parameters which control the falling velocity of water particle are the droplet else, density difference and viscosity of oil. Application of heat will reduce the oil gravity as well as viscosity. However, heat will cause loss of lighter crude fractions. Thus, adjusting the crude viscosity and gravity hy heat has economic limits. Therefore, the most practical approach would be to attempt to increase the particle size. 

Viscosity of oil usually has units of centipoise, although other units are in use. A discussion of the units of viscosity may be found in Chapter 6. 

Oil recommendations by field use. The following comments provide a guide to the types and viscosities of oils usually recommended for internal combustion engines used in the various major fields of applications (Pirro and Wessol, 2001 Wills, 1980). 

Crude oil is pumped from a terminal to a refinery through a 0.3 m diameter pipeline. As a result of frictional heating, the temperature of the oil is 20 deg K higher at the refinery end than at the terminal end of the pipe and the viscosity has fallen to one half its original value. What is the ratio of the pressure gradient in the pipeline at the refinery end to that at the terminal end Viscosity of oil at terminal = 90 mNs/m2. Density of oil (approximately constant) = 960 kg/m3. Flowrate of oil = 20,000 tonne/day. 

The solvent-refined coal (SRC) reactor is normally operated at 850 °F and 2,000 lbf in 2 pressure. Creosote oil is used as solvent In a typical operation, coal particles of approximately 74 jum diameter with a solvent/coal ratio of 2 are used. The slurry is passed through a 2.5-in-i.d., 4-ft-tall reactor. Assuming that coal specific gravity = 1.35, oil specific gravity = 0.9, surface tension of oil under reaction conditions = 5 dyne cm" , viscosity of oil under reaction conditions = 0.7 cP, static slurry height in bed =10 cm, surface tension of liquid (surface tension of water (ow) = 72 dyne cm -... 

Tsuya, Y., Saito, K. and Suzuki, H., Effect of Viscosity of Oil Containing Molybdenum Disulfide on its Load-Carrying Capacity, Lubric. Eng., 31, 619, (1975). 

The long hydrocarbon chain of poly(lnuryl methacrylate) makes the polymer soluble in oil (a mixture of hydrocarbons with mostly 12 or more carbon atoms). At low temperatures the polymer is coiled into halls. Ai higher temperatures the balls uncoil and the polymer exists as long chains. Explain how this helps control the viscosity of oil. 

Galletti compared the viscosities of oils by measuring the area of absorption in a filter paper strip. Stott, Turner, and Sloman determined the viscosity of... 

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